Apparatus for knee surgery and method of use

ABSTRACT

The present invention comprises a set of instruments and a method for their use in preparing a knee joint to receive knee implants. The inventive instruments and method are generally suitable for knee joint surgery. Furthermore, they include features that make them suitable for performing a minimally invasive knee surgery in which a smaller than normal incision is made and oriented to preserve the quadriceps mechanism and protect the suprapatellar pouch. The instruments permit switching from a minimally invasive technique to a standard open technique at any point in the procedure. An illustrative set of instruments for total knee arthroplasty and an associated minimally invasive technique are described.

BRIEF DESCRIPTION OF THE DRAWINGS

[0001] Various embodiments of the present invention will be discussedwith reference to the appended drawings. These drawings depict onlyillustrative embodiments of the invention and are not to be consideredlimiting of its scope.

[0002]FIG. 1 is a front elevation view of a tibia and a femur showingaxes of the knee joint.

[0003]FIG. 2 is a side section view of a knee joint showing typical bonecuts used in replacing the joint surfaces.

[0004]FIG. 3 is a perspective view of knee joint showing aspects ofcomponent positioning.

[0005]FIG. 4 is a perspective view of the knee joint showing theincision planning for a medial surgical approach according to thepresent invention.

[0006]FIG. 5 is a perspective view of the knee joint showing the medialincision according to the present invention.

[0007]FIG. 6 is a perspective view of the knee joint showing theincision planning for a lateral surgical approach according to thepresent invention.

[0008]FIG. 7 is a perspective view of the knee joint showing the lateralincision according to the present invention.

[0009]FIG. 8 is a perspective view of an illustrative embodiment of apatella resection guide according to the present invention.

[0010]FIG. 9 is a top plan view of the patella resection guide of FIG.8.

[0011]FIG. 10 is an exploded perspective view of another illustrativeembodiment of a patella resection guide according to the presentinvention.

[0012]FIG. 11 is a top plan view of the patella resection guide of FIG.10.

[0013]FIG. 12 is a side elevation view of the patella resection guide ofFIG. 10 shown gripping a patella.

[0014]FIG. 13 is a front elevation view of the patella resection guideof FIG. 10.

[0015]FIG. 14 is a perspective view of an illustrative embodiment of anintramedullary distal femoral cutting instrument according to thepresent invention.

[0016]FIG. 15 is a side elevation view of the intramedullary distalfemoral cutting instrument of FIG. 14.

[0017]FIG. 16 is a front elevation view of the intramedullary distalfemoral cutting instrument of FIG. 14.

[0018]FIG. 17 is a side elevation view of the intramedullary distalfemoral cutting instrument of FIG. 14 mounted on a femur.

[0019]FIG. 18 is a side elevation view of another illustrativeintramedullary distal femoral cutting instrument according to thepresent invention mounted on a femur.

[0020]FIG. 19 is a front elevation view of an illustrative embodiment ofa tibial cut guide assembly according to the present invention.

[0021]FIG. 20 is a perspective view of the tibial cut guide assembly ofFIG. 19.

[0022]FIG. 21 is a top plan view of the tibial cut guide assembly ofFIG. 19.

[0023]FIG. 22 is an exploded perspective view of an illustrativeembodiment of a depth gauge for use with the tibial cut guide of FIG. 19according to the present invention.

[0024]FIG. 23 is a perspective view of the tibial cut guide assembly ofFIG. 19 and the depth gauge of FIG. 22 mounted on a tibia.

[0025]FIG. 24 is a perspective view of an illustrative embodiment of afemoral A/P sizer and pin guide assembly according to the presentinvention.

[0026]FIG. 25 is a bottom plan view of the femoral A/P sizer and pinguide assembly of FIG. 24.

[0027]FIG. 26 is a perspective view, from a different viewing angle, ofthe femoral A/P sizer and pin guide assembly of FIG. 24.

[0028]FIG. 27 is a perspective view showing the femoral A/P sizer andpin guide assembly of FIG. 24 being assembled on a distal femur.

[0029]FIG. 28 is a perspective view showing the femoral A/P sizer andpin guide assembly of FIG. 24 fully assembled on a distal femur.

[0030]FIG. 29 is a perspective view showing two reference pins insertedin the distal femur using the femoral A/P sizer and pin guide assemblyof FIG. 24.

[0031]FIG. 30 is a perspective view of an illustrative embodiment of afemoral profile cut block according to the present invention.

[0032]FIG. 31 is a perspective view, from a different viewing angle, ofthe femoral profile cut block of FIG. 30.

[0033]FIG. 32 is a perspective view of the femoral profile cut block ofFIG. 30 mounted on a femur.

[0034]FIG. 33 is a perspective view of an illustrative embodiment of atrochlear cut guide according to the present invention.

[0035]FIG. 34 is a perspective view of another illustrative embodimentof a femoral provisional trochlear cut guide according to the presentinvention mounted on a femur and further showing an illustrativeembodiment of a chisel for use with the cut guide.

[0036]FIG. 35 is a side elevation view of the intercondylar notch guideof FIG. 39.

[0037]FIG. 36 is a perspective view of an illustrative embodiment of anintercondylar notch guide mounted on a femur according to the presentinvention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0038] The present invention relates to methods and instruments forperforming total knee arthroplasty. An incision is made into the kneejoint to expose the bones comprising the joint. Cutting guides are thenused to guide the removal of the articular surfaces that are to bereplaced. Artificial joint components are then positioned to replace theresected bone ends in order to establish the desired alignment andmechanics of the joint. Each aspect of the surgery affects the ultimateoutcome of the procedure. The incision location and size determines theextent to which the bones can be exposed for facilitating the bonecutting steps. The incision also affects the amount of trauma to thesoft tissues surrounding the joint and therefore the pain, time forrecovery, and stability of the joint postoperatively. The design of thecutting guides affects how much exposure is required to place and orientthe guides relative to the bones. The precision of the cuts produced bythe guides affects the stability and longevity of the joint replacement.Finally, the manner in which the joint components attach to one anotherand to the bone affects the amount of exposure required and thestability and longevity of the joint replacement. The inventiveinstruments and method are generally suitable for knee joint surgery.Furthermore, they include features that make them suitable forperforming a minimally invasive knee surgery in which a smaller thannormal incision is made and oriented to preserve the quadricepsmechanism and protect the suprapatellar pouch. The instruments permitswitching from a minimally invasive technique to a standard opentechnique at any point in the procedure.

[0039] In order to better understand the total knee arthroplastyprocedure, it is helpful to understand the relationship of the bones andthe cuts made to orient the implant components. FIGS. 1-3 illustrateseveral aspects of implant orientation. FIG. 1 illustrates various axesof the lower limb in the frontal plane. Axes can be defined for eachsegment of the lower limb. For example, the femur 1 has an anatomic axis2 coinciding generally with its intramedullary canal. It also has amechanical axis 4, or load axis, running from the center of the femoralhead to the center of the knee. The angle 6 between these two axesvaries within the patient population but is on the order of 6°.Likewise, the tibia 3 has an anatomic axis coinciding generally with itsintramedullary canal. The mechanical axis 5 of the tibia runs from thecenter of the knee to the center of the ankle and is generally collinearwith the anatomic axis. The transverse axis, or joint line 8, aboutwhich the knee flexes, is parallel to a line through the medial andlateral femoral condyles and parallel to the tibial plateau. This linesubtends a slight valgus angle of approximately 87° with the mechanicalaxis of the femur and a slight varus angle of approximately 87° with themechanical axis of the tibia. Thus, the distal femur is in slight valgusand the proximal tibia is in slight varus. Normally, the distal femurand proximal tibia are resected to be parallel to the joint line 8, andthus perpendicular to the mechanical axis 4, as indicated at 10 and 12.The intersection of the femoral and tibial mechanical axes, 4 and 5, maysubtend a small angle relative to one another. However, the angle issmall and the mechanical axis of the femur has an approximately normalalignment with the proximal tibia if the knee is uninjured. Thereforethe tibial mechanical axis may be extrapolated to the distal femur todefine the femoral mechanical axis in the distal femur when there is afemoral deformity. Similarly, if there is a deformity in the tibia, themechanical axis of the proximal tibia may be defined by extrapolatingthe femoral mechanical axis. The illustrative procedure described hereinrestores the center of the femoral bead, the knee, and the ankle to alie on a straight line to establish a neutral mechanical axis. Thefemoral and tibial components are oriented perpendicular to this axis inthe frontal plane.

[0040]FIG. 2 illustrates the knee joint from the side or sagittal viewand various bone cuts that may be made to align implant components. Thedistal femur is typically cut 10 perpendicular, in theanterior-to-posterior direction, to the anatomic axis 2 of the femur.The proximal tibial resection 12 is normally cut to match the naturalposterior slope of the proximal tibia relative to the tibial mechanicalaxis 5. The amount of posterior slope 16 relative to a reference line 18perpendicular to the tibial mechanical axis 5 varies in the patientpopulation but is on the order of 7°. The distance between the distalfemoral 10 and proximal tibial 12 cuts along the mechanical axes 4 and 5is the extension gap. Other cuts may be made depending on the componentsthat are to be implanted. These include an anterior femoral cut 20,anterior femoral chamfer cut 22, posterior femoral chamfer cut 24, andposterior femoral cut 26. The patella 7 may also be cut 28 to allow forreplacement of the patellar articular surface. Additional preparation ofthe bone may include drilling or notching the bones to receive pegs,stems, and other extensions from the components (not shown).

[0041]FIG. 3 depicts six aspects of component positioning relative to acoordinate system in which the x-axis 30 corresponds approximately tothe joint line 8, the z-axis 34 corresponds approximately to themechanical axes 4 and 5, and the y-axis 32 is normal to the other two.Position along each of these axes is depicted by arrows. Position alongthe x, y, and z axes determines the medial/lateral (dx) 36,anterior/posterior (dy) 38, and proximal/distal (dz) 40 positioning ofcomponents respectively. Rotation about each of these axes is alsodepicted by arrows. Rotation about the z-axis (rz) 42 correspondsanatomically to external rotation of the femoral component, whilerotation about the x-axis (rx) 44 and y-axis (ry) 46, corresponds toextension plane slope and varus/valgus angle respectively. Depending onthe order of the cuts, and the way that subsequent instruments referenceeach cut, the position of the distal femoral cut 10 can affect thelocation of the joint line (dz), the extension gap, the varus/valgusangle (ry), and the extension plane angle (rx). Likewise, the positionof the proximal tibial cut 12 can affect the varus/valgus angle (ry),extension plane (rx), external rotation (rz), and the joint line (dz) orextension gap. The position of the anterior 20, posterior 26, andchamfer 22 and 24 femoral cuts affect anterior/posterior size andplacement (dy) and external rotation (rz). Finally, the position of pegholes, stem notches, and other similar bone cuts affect medial/lateral(dx) placement of components.

[0042] An illustrative set of instruments for total knee arthroplastyand an associated minimally invasive technique will now be describedwith reference to the drawings. The illustrative technique utilizes alimited exposure approach from the side of the knee as shown in FIGS.4-7. This side approach can be at an oblique angle relative to the frontof the knee or transversely, more directly from the side. The sideapproach permits a minimally invasive knee surgery in which a smallerthan normal incision is made and orients the incision and subsequentbone cuts to preserve the quadriceps mechanism and protect thesuprapatellar pouch. FIGS. 4 and 5 depict a medial approach and FIGS. 6and 7 depict a lateral approach. Reference lines are made on the kneeprior to making the incision. For the medial approach, a curvilinearmedial incision 50 is made from the superior pole 52 of the patella 54to the tibial joint line 56. The outline of the medial femoral condyle58 is also marked. The arthrotomy is in line with the skin incision andincludes a transverse incision 60 beneath the vastus medialis toincrease the exposure of the medial femoral condyle 62. Alternatively, alateral approach may be used. For the lateral approach, the incision 70is made on the lateral side of the patella 72 to the tibial joint line74 and is almost vertical along the side of the patella. The outline ofthe lateral femoral condyle 75 is also marked. The arthrotomy isperformed in a vertical fashion and the iliotibial band 76 is peeledfrom the tibial plateau joint line from anterior to posterior to exposethe lateral femoral condyle 78. No transverse capsular incision is usedfor the lateral approach.

[0043] Throughout the description of the illustrative technique andinstruments, reference will be made to cutting bone. There are manycutters for surgically cutting bone including: oscillating saws,reciprocating saws, gigli saws, end cutting reamers, side cuttingreamers, streams of particles, energy beams, and others known in theart. While the illustrative embodiments depict and describe saw bladeguides for guiding a saw blade to cut bone, any means for cutting boneis contemplated. The slots can be replaced with surfaces, jigs, clamps,and other types of fixtures as appropriate to guide the type of cutterbeing used.

[0044] The preparation of the patella is described first. However, thepatella can be prepared later if desired. Preparing it first results inmore space anteriorly when preparing the distal femur. The illustrativeinstruments allow preparation of the patella without everting it toavoid damage to the patellar mechanism. Alternatively, waiting untilafter the distal femur and/or proximal tibia are prepared allows thejoint to be collapsed to reduce tension in the patellar tendon andligament and improve access to prepare the patella.

[0045] The patella is prepared using a patella resection guide. FIGS. 8and 9 illustrate one embodiment of a patella resection guide 100.Stationary jaw member 102 includes a top surface 104, a bottom surface106, an inner concave surface 108, an opposite outer surface 109, andteeth 110 projecting inwardly from the concave surface 108, adjacent thetop surface 104. Guide arms 112, 114 project from the concave surface108 and connect the concave surface to a pair of handles 116, 118. Theguide arms 112, 114 are generally perpendicular to the jaw member 102and parallel to one another. The pair of handles 116, 118 are coplanarand are attached generally perpendicularly to the guide arms 112, 114and extend in opposite directions from one another. A top portion 111 ofthe stationary jaw 102, including the teeth 110 and top surface 104,projects above the guide arms 112, 114. Translating jaw member 122includes a top surface 124, a bottom surface 126, an inner concavesurface 128, an opposite outer surface 129, and teeth 130 projectinginwardly from the concave surface 128, adjacent the top surface 124.Bores 131, 132 through the translating jaw member 122 provide bearingsurfaces in engagement with guide arms 112, 114 such that thetranslating jaw member 122 may be moved along the guide arms 112, 114 ina motion plane from a first position in which the two jaw members 102,122 are spaced from one another and the translating jaw 122 is nearerthe handles 116, 118 and a second position in which the two jaw members102, 122 are closer to one another and the translating jaw 122 isfarther from the handles 116, 118. This arrangement constrains the jawsto remain parallel to one another as they move relative to one another.A top portion 134, including the teeth 130 and top surface 124, of thetranslating jaw 122 projects above the guide arms 112, 114 such that thetops 104, 124 of the jaws 102, 122 are coplanar. The translating jaw 122further includes a saw guide slot 135 extending through the top portion134 from the outer surface 129 to the inner concave surface 128 parallelto the top surface 124 and extending beyond the attachment point of theguide arms to the handles on either side. The slot 135 is positioned sothat it is above the level of the handles 116, 118 to permit easy accessfor the insertion of a saw blade anywhere across the entire width of theslot 135. The slot 135 defines a cutting plane parallel to the motionplane of the translating jaw 122. Actuator 136 comprises an elongatelever having a jaw engaging end 138, a pivot portion 140, and an inputend 142. The jaw engaging end 138 further includes a slot 144 throughwhich a pin 146 connects the jaw engaging end 138 to the translating jaw122. The jaw engaging end 138 can pivot and translate via the slot 144relative to the pin 146 which is fixed to the translating jaw 122. Theactuator 136 is pivotally constrained by a pin 148 extending through thepivot portion 140 and being fixed to the handle 118. Input end 142extends at an angle to the handle 118 when the jaws 102, 122 are in afirst position in which they are spaced from one another. In use, a usergrips the handles 116, 118 and squeezes the input end 142 of theactuator 136 to reduce the angle between the input end 142 and thehandle 118. As the actuator pivot portion 140 rotates about its pin 148,the jaw engaging end 138 presses against its pin 146 and moves thetranslating jaw 122 toward the stationary jaw 102.

[0046] FIGS. 10-13 illustrate another embodiment of a patella resectionguide 200. Stationary jaw member 202 includes a top surface 204, abottom surface 206, a concave inner surface 208, an opposite convexouter surface 209, and teeth 210 projecting inwardly from the concavesurface 208, adjacent the top surface 204. Guide arms 212, 214 projectfrom the concave surface 208 and connect the concave surface to a pairof handles 216, 218 via rectangular bosses 215, 217. The guide arms 212,214 are generally perpendicular to the jaw member 202 and parallel toone another. The handles 216, 218 are coplanar and are attachedgenerally perpendicularly to the guide arms 212, 214 and extend inopposite directions from one another. In this embodiment, the guide arms212, 214 extend past their connections 215, 217 to the handles 216, 218.A top portion 211, including the teeth 210 and top surface 204, of thestationary jaw 202 projects above the guide arms 212, 214. A translatingjaw member 222 includes a top surface 224, a bottom surface 226, aninner concave surface 228, an opposite convex outer surface 229, andteeth 230 projecting inwardly from the concave surface 228, adjacent thetop surface 224. Cannulated guide sleeves 221, 223 connect to oppositesides of the translating jaw 222 and connect the concave surface 228 toa pair of handles 231, 233. The guide sleeves 221, 223 are coplanar andare generally perpendicular to the translating jaw 222 and parallel toone another. The pair of handles 231, 233 are attached generallyperpendicularly to the guide sleeves 221, 223 and extend oppositely andoutwardly from the translating jaw 222. The guide sleeves 221, 223 haveoutwardly facing slots 225, 227 in their outer wall communicating withtheir inner cannulac. The guide sleeves 221, 223 receive guide arms 212,214 such that the translating jaw member 222 may be moved along theguide arms 212, 214 from a first position in which the two jaw members202, 222 are spaced from one another and the translating handles 231,233 are spaced from the stationary handles 216, 218 and a secondposition in which the jaw members and handles are closer to one another.This arrangement constrains the jaw members to remain parallel andfacing one another while they move relative to one another. A topportion 234, including the teeth 230 and top surface 224, of thetranslating jaw 222 projects above the guide sleeves 221, 223 such thatthe tops 204, 224 of the jaws 202, 222 are coplanar. The translating jaw222 further includes a saw guide slot 235 extending through the topportion 234 from the outer surface 229 to the inner surface 228 parallelto the top surface 224.

[0047] This embodiment further includes a depth gauge 240 having asupport 242 and blade 244. The support 242 includes a blade engaging end246, a resection guide engaging end 248, and a longitudinal axis fromone end to the other. The blade includes first 250 and second 252 endsand center attachment portion 254. The center attachment portion 254 isattached to the blade engaging end 246 of the support 242 with athreaded post extending from the support 242 through the attachmentportion 254 and secured with a nut 255. The first 250 and second 252blade ends are each offset a different distance from the centerattachment portion 254 measured along the support 242 axis. Theresection guide engaging end 248 and the resection guide 200 include anengagement mechanism for selectively attaching the depth gauge 240 tothe resection guide 200. Translating jaw 222 includes a through bore 256extending from the top surface 224 to the bottom surface 226 incommunication with the guide slot 235. Depth gauge support 242 includesa hole 258 retaining a spring 260 and ball 262 plunger in the resectionguide engaging end 248. The ball 262 is biased into engagement with theguide slot 235 when the resection guide engaging end 248 is insertedinto through bore 256. The depth gauge can engage the through bore 256and be supported on either the top surface 224 or bottom surface 226.When it is thus supported, the blade ends 250, 252 can be selectivelyplaced to project over the jaws 202, 222. Each blade end projects todefine a plane a different predetermined axial distance from the guideslot 235.

[0048] Both illustrative embodiments are relatively compact to permitthe stationary jaw to be wedged across the joint between the femur andpatella. Both also facilitate approaching the patella from the lateralor medial side and gripping it on its sides while presenting anunobstructed side-facing saw guide slot. The use of the instrument willbe described relative to the embodiment of FIGS. 10-13. The surgeonfirst determines whether it is desirable to remove a prescribed amountof patellar bone or to leave a prescribed amount and how much in eithercase. To remove a prescribed amount of bone, the depth gauge 240 isattached to the top surface 224 of the translating jaw 222 so that theblade 244 references the posterior side 272 of the patella 270 as shownin FIG. 12. To leave a prescribed amount of bone, the depth gauge 240 isattached to the bottom surface 226 of the translating jaw 222 so thatthe blade 244 references the anterior side 274 of the patella 270. Theamount is established by positioning the blade end 250 or 252 having thecorresponding amount of offset in contact with the patella. Thestationaryjaw 202 is wedged across the joint between the femur andpatella with the top surface 204 facing toward the posterior side 272 ofthe patella 270 and the bottom surface 206 facing toward the femur. Thepatella 270 is placed between the jaws with the depth gauge blade incontact with the appropriate patellar surface and the handles 218, 233and 216, 231 are gripped and squeezed toward one another to bring thejaws 202,222 together to grip the patella 270 medially and laterally. Asaw blade is activated through the saw guide slot 235 to resect thepatella. A locking mechanism can be provided to selectively prevent thejaws from moving away from one another. For example, the guide arms 212,214 can be threaded and provided with nuts at their free ends. After thetranslating jaw is moved toward the stationary jaw, the nuts would beadvanced to prevent the translating jaw from moving backward. Likewise,the guide arms 212, 214 can be grooved and the guide sleeves 221, 223provided with ratcheting palls biased into engagement with the groovessuch that the palls ride freely over the grooves as the jaws are movedtoward one another but the palls engage the grooves and resist motion ofthe jaws away from one another.

[0049] The distal femur is prepared using a distal femoral cut guide.FIGS. 14-17 show an illustrative embodiment of an intramedullary (IM)distal femoral cutting instrument 300 for guiding the distal femoralcut. An IM alignment guide 302 includes a body 304 having front 306 andback 308 surfaces, lateral 310 and medial 312 ends, and first 309 andsecond 311 side surfaces. A through slot 314 communicates from the frontsurface 306 to the back surface 308. A cut guide engaging slot 316extends part way from the back surface 308 toward the front surface 306.The cut guide engaging slot 316 is generally aligned with the throughslot 314 and is wider than the slot 314 side-to-side. The cut guideengaging slot 316 extends laterally to open at the lateral end 310. Aneck 318 projects from the medial end 312 and extends the back surface308 medially. A lug 320 is connected to the end of the neck 318 oppositethe body 304. The lug includes a rounded reference surface 322 thatprojects beyond the back surface 308. A socket 324, having alongitudinal axis, is formed in the reference surface 322. The axis ofthe socket 324 forms a predetermined angle relative to the back surface308. For a medial approach to the knee, the angle will be obtuse and fora lateral approach it will be acute. An intramedullary rod 326 having alongitudinal axis fits into the socket 324 so that the rod 326 axis iscoaxial with the socket axis and extends from the IM alignment guide atthe predetermined angle. The rod 326 is welded in place.

[0050] An IM distal cut guide 330 includes a body 332 with front 334 andback 336 surfaces, medial 338 and lateral 340 surfaces, and first 342and second 344 sides. Three saw blade slots 345 extend through the cutguide 330 from the medial 338 to the lateral 340 surface. The slots 345lie in planes parallel to the front surface 334. A pin tab 346 extendsfrom the back surface 346 and has lateral 348 and medial surfaces 350that taper 353 inwardly from the medial 338 and lateral 340 surfaces ofthe body. Fixation holes 351 extend through the pin tab from the lateralsurface 348 to the medial surface 350. An engagement tab 352 extendsfrom the front surface 334 and has sides 354 and 356 and front surface358. A threaded hole 360 extends from the front surface 358 toward thebody 332. The engagement tab 352 engages the cut guide engaging slot 316with the front surface 334 of the distal cut guide resting against theback surface 308 of the IM alignment guide such that the saw blade slots345 are parallel to the back surface 308 and thus are at thepredetermined angle relative to the IM rod 326. The plane of the middlesaw blade slot intersects the extreme end of the reference surface 322.It is desirable to resect the distal femur perpendicular to themechanical axis of the femur. Therefore, the distal cut guide is alignedsuch that a line perpendicular to the saw blade slots 345 is alignedwith the mechanical axis. This is accomplished by providing a pluralityof IM alignment guides having the angle of the IM rod 326, relative tothe plane of the saw blade slots 345, equal to the difference betweenthe anatomic and mechanical axes of the femur. Because of variation inthe patient population, IM alignment guides having different rod 326angles are provided. For example, angles of 4°, 6°, and 8° have beenfound to be suitable to accommodate most patients. The engagement of thetab 352 and slot 316 allows the distal cut guide 330 to slide relativeto the IM alignment guide 302 from a first position in which the distalcut guide 330 is farther from the IM rod 326 and a second position inwhich the distal cut guide 330 is nearer to the IM rod 326. A handle 361includes a grip portion 362, a threaded stud 363 opposite the gripportion 362, and a shoulder 364 intermediate the grip portion 362 andthe threaded stud 363. The threaded stud 363 extends through the slot314 in the IM alignment guide 302 to threadingly engage the threadedhole 360 in the engagement tab 352 of the distal cut guide 330. As thehandle 361 is rotated to further engage the threaded hole 360, theshoulder 364 bears against front surface 306 of the IM alignment guide302 and the front surface 334 of the distal cut guide 330 is drawn intotight locking engagement with the back surface 308 of the IM alignmentguide 302. By means of the handle 361, the distal cut guide 330 can beslid and locked at any position of its travel along the IM alignmentguide.

[0051] In use, a hole is drilled in the center of the patellar sulcus366 of the distal femur, making sure that the hole is parallel to theshaft of the femur 365 in both the frontal and sagittal planes. The holeprovides access to the IM canal of the femur 365. An IM alignment guide302 is selected as appropriate for a medial or lateral approach andhaving a rod 326 angle that accounts for the difference between theanatomic and mechanical axes of the femur as determined by preoperativetemplating. The IM distal cut guide 330 is attached to the alignmentguide 302 using the handle 361. Using the handle, IM rod 326 is insertedinto the IM canal of the femur 365. The assembly is inserted until thereference surface 322 contacts the intercondylar sulcus 366 with the IMalignment guide 302 projecting toward the exposed side of the knee. Thedistal cut guide 330 is slid in slot 316 until the medial surface 338 isadjacent the bone. In FIG. 17, the distal cut guide 330 is shownadjacent the medial condyle 367. The handle 360 is rotated to lock thedistal cut guide 330 relative to the IM alignment guide 302. Pins 368are then inserted through the holes 351 in the pin tab 346 and into thebone to hold the distal cut guide 330 in place. The taper 353 of themedial side 350 of the pin tab 346 causes it to fit the condylar bonemore closely and therefore more stably. Once the pins are placed, thehandle 361 is unthreaded from the distal cut guide 330 and the IMalignment guide 302 and IM rod 326 are removed from the bone leaving thedistal cut guide 330 pinned to the bone. A saw blade is then directedthrough one of the slots 345 to resect the distal femur. If thereference surface 322 was fully seated in the intercondylar sulcus 366,the middle saw guide slot will resect the distal femur to the depth ofthe sulcus. The other slots provide more or less resection.

[0052]FIG. 18 shows an alternative embodiment of distal femoral cutguide 300 in which the lug 320 and rounded reference surface 322 havebeen omitted. Instead, an IM rod 370 is connected directly to the end372 of the neck 374 of the IM alignment guide. In this embodiment, theIM rod 370 is inserted into the IM canal of the femur 378 until the backsurface 380 contacts the near distal femoral condyle. In this case theback surface 380 contacts the distal medial condyle 382. The plane ofthe middle saw blade slot is offset 10 mm from the back surface 380. Theother slots are offset 6 mm and 14 mm respectively. Thus, theappropriate slot is chosen based on how much bone is to be resected fromthe distal femur relative to the near condyle. Typically, the middle or10 mm slot would be used with a medial approach and less would be usedwith a lateral approach.

[0053] The proximal tibia is prepared using a tibial cut guide. FIGS.19-23 show an illustrative embodiment of a tibial cut guide assembly 400for guiding the proximal tibial cut. The assembly includes a tibialtubercle alignment bar 402, a tibial boom 430, a tibial cut guide 446,and a tibial depth gauge 484 (FIGS. 22-23). The tibial tuberclealignment bar 402 includes an elongate body 404 having an anterior face406, a posterior face 408, first and second side walls 410, 412, adistal end 414, a proximal end 416, and a longitudinal axis running fromthe distal end to the proximal end. A dovetail 417 is formed on aportion of the alignment bar 402 adjacent the anterior face 406. A stop418 projects from the anterior face 406 near one end of the dovetail 417toward the distal end 414 of the alignment bar 402. Extensions 420project perpendicularly from either side 410, 412 of the body 404 nearthe proximal end 416. Fixation holes 421 are formed through theextensions 420 from anterior to posterior for receiving fixation pins. Athreaded bore 422 extends through the alignment bar 402 from theanterior face 406 to the posterior face 408 near the proximal end 416. Aplunger 424 having a threaded shaft 426 and an adjustment knob 427 isreceived in the threaded bore 422 such that rotating the adjustment knob427 moves the plunger 424 anteriorly and posteriorly to change thespacing from the end of the plunger 424 to the posterior face 408. Acannula 428 extends through the plunger 424, shaft 426, and knob 427 toallow a pin to pass.

[0054] A tibial boom 430 includes a body 431 having an anterior face432, a posterior face 433, a proximal end 434, a distal end 435, andfirst and second sides 436, 437. A boss 438 projects from the anteriorface and a dovetail groove 439 is formed into the posterior face. Athreaded bore is formed through the boss 438 from the anterior face 432to the dovetail groove 439. A set screw 440 is received in the threadedbore such that rotating the set screw 440 moves it into and out of thedovetail groove 439. Extension bars 442 extend from the first and secondsides 436, 437. The extension bars 442 are “D”-shaped in that they aregenerally cylindrical with a flat 443 along one side. The extension bars442 define a longitudinal axis along their length that is perpendicularto the dovetail groove 439. The tibial boom 430 is mounted on thealignment bar 402 with the dovetail groove 439 engaging the alignmentbar dovetail 417 such that the boom 430 can translate along thelongitudinal axis of the alignment bar between a first position nearerthe proximal end 416 of the alignment bar 402 and a second positionfurther from the proximal end 416 of the alignment bar 402. The setscrew 440 is operable to lock the tibial boom 430 in place by turningthe set screw 440 so that it moves into the dovetail groove 439 toengage the dovetail 417. When the tibial boom is unlocked, it can slidefreely distally until it abuts the stop 418 which prevents it fromsliding further distally. In this way, the tibial boom 430 can be leftunlocked and resting against the stop 418 ready to be moved intoposition. The longitudinal axis of the tibial tubercle alignment bar 402and the longitudinal axis of the extension bars 442 together define aguide plane.

[0055] A tibial cut guide 446 includes a cutting head 448 having aproximal face 450, a distal face 452, opposite side faces 454, 456, aconcave posterior face 458, and a convex anterior face 460. A saw guideslot 462 extends through the cutting head 448 from the anterior face 460to the posterior face 458 generally parallel to the proximal face 450.Fixation holes 464, 466 also extend through the cutting head 448 fromanterior to posterior. The smaller holes 464 are sized to receiveconventional fixation pins, while the larger hole 466 is sized toreceive a spring pin. Proximal face 450 includes a through bore 468extending from the proximal face 450 to at least the saw guide slot 462for receiving a depth gauge. In the illustrative embodiment, the bore468 extends all the way through the cutting head 448 to ease assemblyand cleaning. The cutting head 448 is supported on a base 472 by a leg474. The base 472 is a cylinder having a longitudinal axis and proximal471 and distal 473 faces. Two pairs of “D”-shaped transverse bores480,482 extend through the base 472 perpendicular to its longitudinalaxis, the flat portion of the “D”-shaped holes also being perpendicularto the base axis. A threaded axial bore 476 in the distal face 473communicates with the path of the “D”-shaped holes 480, 482 and receivesa set screw 478. The leg 474 attaches to the base 472 adjacent theproximal face 471 and angles away from the base 472 to support thecutting head 448 in a position offset from the base 472 axis with thesaw guide slot 462 defining a cutting plane perpendicular to thelongitudinal axis of the base 472.

[0056] The tibial cut guide 400 is provided with a depth gauge 484having a support 485 and a blade 486. The support 485 includes a bladeengaging end 487, a resection guide engaging end 488, and a longitudinalaxis from one end to the other. The blade 486 includes first 489 andsecond 490 ends and a center attachment portion 491. The centerattachment portion 491 is attached to the blade engaging end 487 with athreaded post 496 extending from the support 485 through the attachmentportion 491 and secured with a nut 492. The first 489 and second 490blade ends are each offset a different distance from the centerattachment portion 491 measured along the support 485 axis. The depthgauge support 485 includes a hole 493 retaining a spring 494 and ballplunger 495. The ball 495 is biased into engagement with the guide slot462 when the resection guide engaging end 488 is inserted into thethrough bore 468. When it is thus supported, the blade ends 489, 490,can be selectively positioned to project posteriorly over a tibial bone.Each blade end projects to define a point a different predeterminedaxial distance above the saw guide slot 462.

[0057] The tibial cut guide 446 is assembled to the tibial boom 430 bysliding one of the “D”-shaped extension bars 442 through one pair 482 ofthe “D”-shaped holes 480,482. One pair of holes 482 provides for a leftknee medial/right knee lateral orientation while the other 480 providesfor a left knee lateral/right knee medial orientation. Thus assembled,the cutting head 448 is supported in a position proximal and posteriorto the base 472. The set screw 478 can be tightened until it engages theflat 443 of the extension bar 442 to lock the cut guide 446 in positionon the extension bar 442. Thus locked, the longitudinal axis of the base472 is perpendicular to the flat 443 of the extension bar 442 resultingin the saw guide slot 462 being parallel to the flat 443. The angle ofthe flat 443, and thus the saw guide slot, relative to the guide planedefined by the alignment bar 402 and extension bar 442 axes is theposterior slope angle of the tibial cut guide assembly 400. Tibial booms430 providing varying degrees of posterior slope may be provided. Forexample, having two booms 430, one with the flat 443 rotated 3° and theother with the flat rotated 7° would allow the surgeon to choose to cutthe tibia with 3° or 7° of posterior slope.

[0058] In use, a tibial boom 430 is selected having the desiredposterior slope angle. The tibial boom is assembled to the alignment bar402 and allowed to slide all the way down to rest on the stop 418. Theplunger 424 is positioned proximal of the tibial tubercle and centeredmediolaterally with the medial third of the tibial tubercle. A pin isinserted through the cannula 428 of the plunger 424 to stabilize thealignment guide. Alternatively, a pin can be placed proximal of thetibial tubercle and centered mediolaterally with the medial third of thetibial tubercle and the cannula 428 then slipped over the pin until theplunger 424 contacts the patient. The distal end 414 of the alignmentbar 402 is adjusted mediolaterally so that the guide is aligned with themechanical axis of the tibia. In the sagittal plane, the alignment bar402 is adjusted so that it is parallel to the anterior tibial shaft.Proximally, this adjustment is made by turning the knob 427 to move theplunger 424 anterioposteriorly. Additional pins are placed throughfixation holes 421 to further secure the alignment bar 402. Thisestablishes the position of the guide plane relative to the tibia. Now,as the tibial cut guide 446 is positioned along the boom 430 and theboom is adjusted up and down, the saw guide slot 462 will be constrainedto parallel planes of posterior slope having the same angular relationto the guide plane. Thus, the tibial cut guide 446 can now be adjustedmedial-laterally and proximal-distally without changing the varus-valgusorientation or the posterior slope of the resection plane.

[0059] The tibial cut guide 446 is assembled to the tibial boom usingthe appropriate pair of holes 480, 482 for medial/lateral orientation ofthe cut guide 446. The tibial depth gauge 484 is inserted into the topof the tibial cut guide 446 with the blade end 489, 490 corresponding tothe desired resection level oriented over the tibia. The tibial cutguide 446 is positioned by moving the tibial boom 430 vertically untilthe depth gauge 484 references the desired spot on the tibial surfaceand sliding the cut guide medial-laterally on the extension bar 442 sothat it is adjacent the tibia. This position is maintained by tighteningthe boom set screw 440 and the cut guide set screw 478. Pins and/orscrews can then be placed in fixation holes 464, 466 to stabilize thetibial cut guide. The depth gauge is removed and a saw blade is insertedthrough the saw guide slot 462 to cut the proximal surface of the tibia.

[0060] FIGS. 24-29 show an illustrative embodiment of a femoral A/Psizer assembly 500 for determining femoral anterior/posterior (A/P) sizeand placing reference datums for guiding the femoral box cuts. Theassembly includes an A/P sizer base 502, an external rotation plate 525,an A/P sizing tower 540, an anterior boom 550, a drill guide slide 560,a parallel pin drill guide 570, and an alignment pin 579. The A/P sizerbase 502 includes a plate-like body 503 having a front surface 504, aback surface 505, an anterior edge 506, a posterior edge 507, and sidesurfaces 508,509. Posterior condyle referencing feet 510, 511 extendperpendicularly from the front surface 504 and define a posteriorreference plane with their top surfaces 512 and 513. Internally threadedboss 514 projects from one side 508 of the sizer base 502 to threadablyreceive a handle 515. Three alignment holes 516 extend through the sizerbase 502 from the front surface 504 to the back surface 505. Acountersunk pivot pin hole 517 extends through the sizer base 502 fromthe front surface 504 to the back surface 505. An anterior extension 518projects from the anterior edge 506 to support a hollow, cylindricaltower bushing 519 having a top surface 521 and a bore 520 with alongitudinal axis parallel to the front and back surfaces 504, 505 andperpendicular to the posterior condyle referencing feet 510, 511. Athrough hole in the side of the tower bushing 519 receives a set screw522 in communication with the bore 520.

[0061] An external rotation plate 525 includes a plate-like body 526having a front surface 527 a back surface 528, an anterior edge 529, aposterior edge 530, and side surfaces 531, 532. A drill slide bushing533 is connected to, and projects from, one side 532 of the externalrotation plate 525. The drill slide bushing 533 includes a “D”-shapedbore 534 having a longitudinal axis parallel to the front surface 527. Athrough hole in the side of the drill slide bushing 533 threadablyreceives a set screw 524 in communication with the flat side of the“D”-shaped bore. Three, alignment holes 535 extend through the externalrotation plate 525 from the front surface 527 to the back surface 528. Apivot pin hole 536 extends through the external rotation plate 525 fromthe front surface 527 to the back surface 528.

[0062] The external rotation plate 525 is mounted on the A/P sizer base502 with the external rotation plate front surface 527 flat against thesizer base back surface 505. A pin 537 secured in the pivot pin holes517, 536 holds the assembly together and permits planar rotation of theexternal rotation plate 525 relative to the sizer base 502. Thealignment holes 516, 535 are positioned so that a pair of holes alignswhen the external rotation plate 525 is rotated relative to the sizerbase 502 at each of 3°, 5°, and 7° as measured between a lineperpendicular to the top surfaces 512, 513 of the posterior condylereferencing feet 510, 511 and the drill slide bushing 533 axis.

[0063] A femoral A/P sizing tower 540 includes a shaft 541 having afirst end 542, a second end 543, and a longitudinal axis extending fromthe first end to the second end. A collar 544, connected to the secondend 543 of the sizing tower 540, includes a through hole 545 having anaxis perpendicular to the longitudinal axis of the shaft 541. A keyway546 is cut in the side of the collar 544 opposite the shaft 541. FemoralA/P size indicia 547 are inscribed on the shaft 541. The sizing tower540 is mounted on the A/P sizer base 502 with its shaft 541 slidablyreceived within the tower bushing 519 in coaxial relation such that thesizing tower 540 is free to slide up and down, and rotate about, theircoincident axes. An anterior boom 550 includes a handle 551 and a shaft552 having a common longitudinal axis. A probe 553 extends beyond theshaft 552 and bends away from the shaft axis to a probe tip 554 that isoffset a predetermined distance from the shaft 552 axis. A key 555extends longitudinally from the handle 551 and overlies a portion of theshaft 552. The anterior boom 550 is mounted in the collar 544 of thesizing tower 540. The diameter of the probe 553 is smaller than thekeyway 546 and the diameter of the shaft 552 fits closely with thethrough hole 545. Thus, the anterior boom 550 can be mounted by movingthe probe 554 down through the keyway 546 and then sliding the shaft 552into of the through hole 545. As the shaft 552 is slid into place, thekey 555 engages the keyway 546 to prevent the anterior boom 550 fromrotating about its shaft 552 axis. The handle 551 abuts the collar 544to prevent the anterior boom 550 from further translating along itsshaft axis. Thus mounted, the probe tip 554 is in a predeterminedposition relative to the indicia 547 of the sizing tower 540. As thesizing tower 540 is moved up and down in the tower bushing 519, theprobe tip 554 moves up and down in known relation to the top surfaces512, 513 of the posterior condyle referencing feet 510, 511. Thisrelationship is indicated by the position of the indicia 547 adjacentthe top surface 521 of the tower bushing 519. The sizing tower 540 canbe locked in position within the tower bushing bore 520 by tighteningthe set screw 522.

[0064] A drill guide slide 560 includes a base 561 having a dovetailprofile 562 defining a longitudinal dovetail axis. A support arm 563extends from the base 561 perpendicular to the dovetail and the dovetailaxis. The support arm 563 is “D”-shaped, being generally cylindricalwith one side milled flat 564. The support arm 563 is received in thebore 534 of the drill slide bushing 533 for sliding movement along thebore axis. The “D”-shape of the arm 563 and bore 534 prevents the armfrom rotating. The support arm 563 can be locked axially within the bore534 by tightening the set screw 524 so that it bears against the flat564.

[0065] A parallel pin drill guide 570 includes a body 571 having top572, bottom 573, front 574, back 575, and side 576, 577 surfaces. Adovetail groove 592, having a longitudinal dovetail groove axis, isformed from side-to-side in the bottom surface 573. Drill guide holes593 extend through the body 571 from side-to-side. The guide holes 593each have a longitudinal axis that is parallel to the other and parallelto the longitudinal axis of the dovetail groove 592. An anterioralignment hole 578 extends through the body 571 from side-to-side toreceive an alignment pin 579. The parallel pin drill guide 570 ismounted on the drill guide slide 560 with the base dovetail 562engaging, and coaxially aligned with, the dovetail groove 592 so thatthe parallel pin drill guide 570 can slide along the coincident axes.Thus assembled, the guide hole 593 axes are parallel to the frontsurface 504 of the A/P sizer base and they are at an angle relative tothe top surfaces 512, 513 of the posterior condyle referencing feet 510,511 as determined by the rotated position of the external rotation plate525. The alignment pin 579 can be extended over the shaft 552 of theanterior boom 550 to act as a feeler gauge to reference the verticalposition of the drill guide 570 to the vertical position of the probetip 554. By adjusting the parallel pin drill guide up and down until thealignment pin 579 rests on the shaft 552, the guide holes 593 can bepositioned at a predetermined position relative to the probe tip 554. Inthis illustrative embodiment, the A/P sizer base 502 and the externalrotation plate 525 are hinged on the lateral side in order to adjustexternal rotation. Also in this illustrative embodiment, only one drillslide bushing 533 (medial or lateral) is provided on each externalrotation plate 525. Because of this design, four A/P sizer base 502 andexternal rotation plate 525 combinations would be provided to allow formedial and lateral approaches to both a left and a right knee.

[0066] In use, the handle 515 is assembled to the appropriate A/P sizer500 depending on whether the operative knee is left or right and whetherthe approach is medial or lateral. In the illustrative embodiment, theA/P sizer 500 is placed so that the front surface 504 of the A/P sizerbase is flat against the resected distal femur 585 and the top surfaces512, 513 of the feet 510, 511 are flush against the posterior condyles586, 587. Alternatively, the A/P sizer could be placed on an unresectedfemur and the distal femoral cut made later. In such a case, the distalcut depth could also be set with the A/P sizer. The A/P sizer 500 offersthree methods for setting external rotation: the epicondylar axis, theA/P axis, or the posterocondylar axis. To use the epicondylar axis, aline is drawn between the medial and lateral epicondyles 588, 589. Thefeet 510,511 are placed against the posterior condyles 586, 587 and theanterior edge 529 of the external rotation plate 525 is then setparallel to the line drawn between the epicondyles 588, 589. The pair ofalignment holes 516, 535 that most nearly align are then aligned and thesizer 500 is secured by inserting a spring pin 590 through the alignedholes 516, 535. Likewise, to use the A/P axis, Whiteside's line is drawnalong the A/P axis. The feet 510,511 are placed against the posteriorcondyles 586, 587 and the anterior edge 529 of the external rotationplate 525 is then set perpendicular to the line drawn along the A/Paxis. The pair of alignment holes 516, 535 that most nearly align arethen aligned and the sizer 500 is secured by inserting a spring pin 590through the aligned holes 516, 535. To use the posterior condylar axis,the appropriate set of alignment holes 516, 535 are aligned tocorrespond to 3°, 5°, or 7° of external rotation while the feet 510, 511are kept against the posterior condyles 586, 587 and a spring pin 590 isinserted through the aligned holes.

[0067] Once rotation is established, the A/P sizing tower 540 isinserted into the tower bushing 519. The anterior boom 550 is insertedinto the collar 544 with the key 555 engaging the keyway 546. The probetip 554 is positioned on the anterior cortex 591 of the femur. Theposition of the probe tip 554 will determine the exit point of theanterior bone cut and the ultimate position of the femoral jointcomponent. The vertical position of the A/P sizing tower 540 is lockedby tightening the set screw 522. The femoral size is indicated by theindicia 547 appearing above the top surface 521 of the tower bushing519. The drill guide slide 560 is mounted in the drill slide bushing 533and the parallel pin drill guide 570 is mounted on the drill guide slide560. The alignment pin 579 is inserted through the anterior alignmenthole 578. The drill guide 570 and drill guide slide 560 are raised untilthe alignment pin 579 rests on top of the shaft 552 to set the A/Pposition of the femoral component. The vertical position of the drillguide slide 560 is locked by tightening the set screw 524. The drillguide 570 is slid along the drill guide slide 560 until it is adjacentthe femur. A hole is drilled into the femur through one of the guideholes 593 and a headless pin 594 is placed in the drilled hole toestablish a datum that records the rotation angle and A/P position insuch a way that the datum can be subsequently referenced by bone cuttingguides to produce bone cuts relative to the rotation and positioninformation. The illustrative embodiment describes using pins set in thefemur as datums. Other datums that can record the information arecontemplated and include by way of example: one or more holes, screws,notches, and grooves. A single pin can record the external rotation andA/P position. However, rotation about the pin axis is not constrained bya single pin without some other reference such as the distal femur. Ifdesired, a second hole can be drilled into the femur through the otherguide hole 593 and a second headless pin 595 placed to constrainrotation about the pin axes and also to provide a more stable datum. Allcomponents of the A/P sizer assembly 500 are now removed leaving theheadless pins 594, 595 in place to locate the femoral profile cut.

[0068] The femoral box cuts, or profile, are cut using a femoral profilecut block. FIGS. 30-32 show an illustrative femoral profile cut block600 for guiding the anterior, posterior and chamfer cuts on the distalfemur. The cut block 600 is generally an “L”-shaped body having inner602 and outer 604 distal surfaces, inner 606 and outer 608 sidesurfaces, an anterior surface 610, and a posterior surface 612. A pairof pin reference holes 614 extends through the side of the cut block 600from the outer side surface 608 to the inner side surface 606 forreceiving the headless femoral reference pins 594, 595. The referenceholes 614 are elongated proximal-to-distal to allow proximal-to-distalmotion relative to a reference pin while still constraining the A/Pposition and external rotation relative to the pin. This arrangementallows the proximal-to-distal position of the block 600 to be referencedfrom the distal surface 602 rather than the holes 614. A side fixationhole 616 extends through the side of the cut block 600 from the outerside surface 608 to the inner side surface 606 for receiving a fixationpin. A distal fixation hole 618 extends through the distal side of thecut block 600 front the outer distal surface 604 to the inner distalsurface 602 for receiving a fixation pin. Anterior 620, anterior chamfer622, posterior 624, and posterior chamfer 626 saw guide slotscorresponding to the anterior, posterior, and chamfer surfaces of afemoral implant box are positioned in fixed predetermined relationshipto the pin reference holes 614. The slots sweep around the cut block 600from the side surfaces to the distal surfaces to permit a saw blade tobe directed medial-laterally and proximal-distally to make a completecut across the femur through each slot. A visualization window 628extends from the outer distal surface 604 to the inner distal surface602 to allow direct visualization of the distal femur during positioningof the cut block 600 and cutting of the distal femur. When surgery isperformed through a small surgical incision, this window 628 permits thesurgeon to observe the saw blade in action. The medial side of theinstrument is contoured to match the incision by providing a notch 629to provide soft tissue clearance for the illustrative minimally invasivesurgical procedure. For a lateral approach, a cut block is provided withthe lateral side contoured to match the incision.

[0069] In use, the appropriate size femoral profile cut block 600 ispositioned over the headless pins 594, 595 with the pins engaging pinreference holes 614 which sets the A/P position and external rotation ofthe cut block 600. The cut block 600 is secured to the femur with aspring pin 630 through the distal fixation hole 618. As the pin 630 istightened, the cut block 600 can move proximally due to the elongatedholes 614 until the inner distal surface 602 is stably seated on thedistal femur. An additional spring pin 632 can be inserted from the sidethrough the side fixation hole 616 to further stabilize the cut block600. A saw blade can now be used to cut the femoral profile by directingit through the posterior 624, posterior chamfer 626, anterior 620, andanterior chamfer 622 saw guide slots. The cuts can be made in any order;however, by making them in this order optimal stability of the cut guidecan be maintained. After the cuts are made, the cut block and headlesspins are removed.

[0070] Where required, a trochlear recess or notch is cut using atrochlear notch guide. This would be required when a femoral implant hasa trochlear recess or notch that extends into the anterodistal portionof the femoral box profile. For example, in an implant where a deeperpatellar groove is incorporated, extra material may be added to theinside of the implant to accommodate the deeper groove. Consequently, acutout must be formed on the bone to receive this extra material for aconforming fit between the implant and bone. FIG. 33 shows anillustrative embodiment of a trochlear cut guide 800. The trochlear cutguide 800 comprises a generally “L”-shaped body including an anteriorportion 802 having an external anterior surface 804, an internalanterior surface 806, opposing sides 808, 810, a proximal side 812, anda distal side 813. An anterior chisel guide slot 814 extends through theanterior portion 802 from the external anterior surface 804 to theinternal anterior surface 806. The chisel guide slot 814 comprises aproximal slot opening 816 and two side slot openings 818, 820. A distalguide portion 830 extends at an angle from the distal side 813 of theanterior portion 802. The distal portion 830 includes an external distalsurface 832, an internal distal surface 834, opposing sides 836, 838, aposterior side 840, and an anterior side 841. The anterior side 841 ofthe distal portion 830 and the distal side 813 of the anterior portion802 blend at a radius 815 to form the connection between these twoportions. A distal chisel guide slot 842 extends through the distalportion 830 from the external distal surface 832 to the internal distalsurface 834. The chisel guide slot 842 comprises a posterior slotopening 844 and two side slot openings 846, 848. Ears 850 extend fromeach side 836, 838 of the distal portion 830. The ears 850 includefixation holes 852 and 854. Distal drill guide holes 856 guide a drillfor making peg receiving holes in the distal femur. The chisel guideslots 814, 842 are aligned with the proximal slot opening 816 beingcoplanar with the posterior slot opening 844 and the anterior portionside slot openings 818, 820 being coplanar with the distal portion sideslot openings 846, 848. A cutting instrument inserted into distal chiselguide slot 842 will exit anterior chisel guide slot 814 and cut a notchacross the anterodistal aspect of the femur.

[0071]FIG. 34 shows an alternative embodiment of a trochlear cut guidecomprising a slotted femoral provisional 860. This trochlear cut guidefacilitates making the trochlear notch cut and drilling the distal pegholes in similar fashion as trochlear cut guide 800. However, theslotted provisional 860 includes an external articulating surface thatmatches the external articulating surface of a corresponding femoralimplant. This pennits the option of finishing the tibial and patellarcuts and conducting a trial reduction in which provisional implants ofall of the knee components are inserted and flexed through their rangeof motion to check implant sizing and function. The mediolateralposition of the slotted femoral provisional 860 can be adjusted andretested before making the trochlear notch cut and drilling the distalpeg holes which set the mediolateral position. The slotted provisional860 articular surfaces include an anterior patellar flange 864connecting arcuate, spaced apart distal 865, 866 and posterior 867, 868condyles. Opposite the articulating surfaces are the internal boxsurfaces including anterior 870, anterior chamfer 871, distal 872,posterior chamfer 873, and posterior 874 box surfaces. An anteriorchisel guide slot 875 extends through the anterior flange 864 from theexternal anterior surface to the internal anterior box surface 870. Thechisel guide slot 875 comprises a proximal slot opening 876 and two sideslot openings 877, 878. A distal chisel guide slot 879 extends throughthe distal condyles 865, 866 from the external distal surface to theinternal distal box surface 872. The distal chisel guide slot 879comprises a posterior slot opening 880 and two side slot openings 881,882. Distal drill guide holes 883 guide a drill for making peg receivingholes in the distal femur. Anterior chisel guide slot 875, distal chiselguide slot 879, and drill guide holes 883 are configured and functionlike those of the trochlear cut guide 800 of FIG. 33.

[0072] The use of the trochlear notch cutting guide will be describedwith reference to the slotted provisional embodiment 860 of FIG. 34. Theappropriate size femoral provisional is placed on the end of the femur884. The appropriate mediolateral position can be established visuallyor, in the case of the slotted provisional 860, by trial reduction. Ahole is drilled into the distal femur through one of the drill guideholes 883 and a holding peg (not shown) is inserted. A hole is drilledinto the femur through the other one of the drill guide holes 883 andanother holding peg is inserted. A chisel 885 having a three sided bladeconfigured to engage the chisel guide slots 875, 879 is inserted intothe distal chisel guide slot 879. The chisel 885 is driven across thedistal femur to engage the anterior chisel guide slot 875 and cut thetrochlear notch.

[0073] Posterior stabilized femoral components have a protruding cambox. A piece of bone is cut from the intercondylar region of the distalfemur using an intercondylar notch guide to accommodate this cam box.FIGS. 35-36 show an illustrative embodiment of an intercondylar notchguide 900. The notch guide 900 comprises a generally “L”-shaped bodyincluding an anterior portion 901 having an anterior outer surface 902and an anterior inner surface 904. Spaced apart condylar portions 906,908 depend at an angle from the anterior portion 901 to define a“U”-shaped opening 907 between them. The condylar portions have distalinner 910 and outer 912 surfaces. A trochlear ramp 914 projects from theanterior inner surface 904. The ramp 914 has a planar, distal saw guidesurface 916 that intersects the anterior outer surface 902 and definesthe closed end of the “U”-shaped opening 907. The condylar portions 906,908 have parallel, spaced apart, inner side walls 918, 920. The sidewalls 918, 920 define medial and lateral saw guide surfacesperpendicular to distal saw guide surface 916. Each of the condylarportions 906, 908 includes a threaded peg hole 922, 924. Pegs canoptionally be threaded into the holes to extend from the distal innersurface 910. In use, the appropriate size intercondylar notch guide 900is chosen and placed on the distal femur. The trochlear ramp 914 fitswithin the trochlear notch cut in the prior step to position the notchguide mediolaterally. Additionally, pegs can be threaded into peg holes922, 924 to align mediolaterally with the femoral peg holes drilled inthe prior step. A saw blade is then guided along the distal 916 and side918, 920 saw guiding surfaces to cut the base and sides of theintercondylar notch. The cut bone and intercondylar notch guide are thenremoved.

[0074] It will be understood by those skilled in the art that theforegoing has described illustrative embodiments of the presentinvention and that variations may be made to these embodiments withoutdeparting from the spirit and scope of the invention defined by theappended claims. For example the illustrative embodiments depict usingsaw guides and blades to make the bone cuts. However, the claimedmethods and alignment guides could also be used with other bone removalsystems to set their reference bases to achieve the desired position androtation of prepared bone surfaces.

What is claimed is:
 1. A patella resection guide for guiding a cutter to cut a patella having an anterior side, an opposite posterior side, a medial side and a lateral side, the patella resection guide comprising: a first jaw for engaging said medial side of said patella; a second jaw for engaging said lateral side of said patella; means for moving the first jaw relative to the second jaw from a first position in which the jaws are disengaged from said medial and lateral sides of said patella to a second position in which the jaws are engaged with said medial and lateral sides of said patella, the means being actuable from a location that is medial or lateral of said patella; and means for guiding a cutter to cut said patella.
 2. The patella resection guide of claim 1 further comprising means for gauging the amount of bone to be resected.
 3. The patella resection guide of claim 1 further comprising means for gauging the amount of bone that will remain after the patella is cut.
 4. A patella resection guide for guiding a cutter to cut a patella having an anterior side, an opposite posterior side, a medial side and a lateral side, the patella resection guide comprising: a first jaw shaped to engage said medial side of said patella; a second jaw shaped to engage said lateral side of said patella; a handle connecting the first and second jaws in translating relationship, the handle being actuable to move the jaws from a first position in which the jaws are disengaged from said medial and lateral sides of said patella to a second position in which the jaws are engaged with said medial and lateral sides of said patella, the handle being actuable from a location that is medial or lateral of said patella.
 5. The patella resection guide of claim 4 wherein the jaws are have curved faces for engaging curved sides of said patella.
 6. The patella resection guide of claim 4 wherein the handle comprises a guide arm connecting the first and second jaws, at least one of the first and second jaws mounted for translation along the guide arm to move from the first position to the second position.
 7. The patella resection guide of claim 6 wherein the jaws remain parallel as they are moved from the first to second positions.
 8. The patella resection guide of claim 7 wherein the handle comprises an actuator pivotably mounted on the handle at a first end and connected to one of said first and second jaws at a second end such that pivoting the actuator moves the jaws between the first and second positions.
 9. The patella resection guide of claim 6 wherein the handle further comprises a first grip portion connected to the first jaw and a second grip portion connected to the second jaw, the first and second grip portions being parallel to one another, such that pressing the first and second grip portions together in parallel manner causes at least one of the first and second jaws to translate along the guide arm from the first position to the second position.
 10. The patella resection guide of claim 4 further comprising a depth gauge removably mountable on the first side of the resection guide to indicate the amount of bone to be removed from said patella and alternately mountable on the second side of the resection guide to indicate the amount of bone to remain on said patella.
 11. The patella resection guide of claim 4 further comprising a cutter guide to guide a cutter.
 12. The patella resection guide of claim 11 wherein the cutter is selected from the list consisting of a saw blade, a side cutting reamer, a end cutting reamer, and a water jet cutter.
 13. A patella resection guide comprising: a first side; a second side; and a depth gauge removably mountable on the first side of the resection guide to indicate the amount of bone to be removed from said patella and alternately mountable on the second side of the resection guide to indicate the amount of bone to remain on said patella.
 14. A patella resection guide for guiding a cutter to cut a patella having an anterior side, an opposite posterior side, and a periphery around the patella, the patella resection guide comprising: a first jaw member shaped to engage said periphery of said patella; a second jaw member shaped to engage said periphery of said patella, the second jaw member connected to the first jaw member in translating relation; a first handle connected to the first jaw member; a second handle connected to the second jaw member, the second handle being actuable to move the second jaw member in a motion plane toward and away from the first handle; and a cutter guide adjacent the jaws, the cutter guide able to guide a cutter to cut in a plane parallel to the jaw motion plane.
 15. A patella resection guide for guiding a cutter to cut a patella having an anterior side, an opposite posterior side, and a periphery around the patella, the patella resection guide comprising: a first jaw member shaped to grip said periphery of said patella; a second jaw member shaped to grip said periphery of said patella; a support member connecting the first jaw member in translating relationship to the second jaw member, the support constraining the jaw members to remain parallel when they move relative to one another; a handle actuable to move the first and second jaw members in a motion plane from a first position in which the jaw members are further from one another to a second position in which the jaw members are nearer one another; a cutter guide adjacent the jaws, the cutter guide able to guide a cutter to cut in a plane parallel to the jaw motion plane.
 16. A method comprising the steps of: providing a patella resection guide having patella gripping jaws and a cutter guide; making an incision on at least one of the medial and lateral sides of a knee to expose said patella from the side; gripping the medial and lateral sides of the patella with the jaws of the patella resection guide while the patella remains in its normal orientation relative to the femur; and guiding a cutter with the cutter guide through the incision from the side of the knee to resect the patella.
 17. The method of claim 16 further comprising the steps of: providing a gauge alternately connectable to a first side of the patella resection guide to indicate the amount of bone to be removed and to a second side of the patella resection guide to indicate the amount of bone to remain; determining whether to gauge the amount of bone to remove or the amount of bone to remain; attaching the depth gauge to the appropriate side; and cutting the bone.
 18. A femoral distal cut guide for cutting a femur, the femur having a frontal plane, a sagittal plane, a femoral head adjacent a hip joint, a femoral shaft with an intramedullary canal, a condylar portion adjacent a knee joint having a medial side and a lateral side, an anatomic axis lying along the intramedullary canal, and a mechanical axis lying along a line from the center of the femoral head to the center of the knee joint, the cut guide comprising: an intramedullary rod having a longitudinal rod axis; and a distal cut guide, the distal cut guide mounted on the intramedullary rod at an angle to the longitudinal rod axis, as measured in the frontal plane, so that aligning the intramedullary rod with the anatomic axis and extending the distal cut guide toward the side of the knee orients the distal cut guide to guide a cutter from the side of the knee to cut the distal femur perpendicular to the mechanical axis.
 19. The femoral distal cut guide of claim 18 further comprising an intramedullary alignment guide connected to the intramedullary rod and having a longitudinal guide axis at an angle to the longitudinal rod axis, as measured in the frontal plane, so that when the rod is aligned with the anatomic axis and the longitudinal guide axis is parallel to the frontal plane, the longitudinal guide axis is perpendicular to the femoral mechanical axis and extended toward one of the medial and lateral sides of the knee.
 20. The femoral distal cut guide of claim 19 further comprising a distal cut guide mounted for motion parallel to the longitudinal guide axis with the distal cut guide directed toward one of the medial and lateral sides of the knee, the distal cut guide able to be translated along the longitudinal guide axis to a position adjacent one of the medial and lateral sides of the knee.
 21. The femoral distal cut guide of claim 20 wherein the intramedullary alignment guide further includes a reference surface for contacting a distal femoral condyle to position the distal cut guide to make a cut at a predetermined distance from the femoral condyle.
 22. The femoral distal cut guide of claim 20 wherein the intramedullary alignment guide further includes a reference surface for contacting said intercondylar sulcus to position the distal cut guide to make a cut at a predetermined distance from the intercondylar sulcus.
 23. A method of cutting a distal femur comprising the steps of: providing a distal cut guide having an intramedullary rod; making an incision on at least one of the medial and lateral sides of a knee to expose the distal femur from the side; inserting the intramedullary rod into an intramedullary canal of the femur; orienting the distal cut guide so that it extends toward one of the medial and lateral sides of the femur; and guiding a cutter with the cutter guide to cut the distal femur from the side to form a planar distal surface.
 24. The method of claim 23 further comprising the steps of: providing an alignment guide extending at an angle to the intramedullary rod; providing a distal cut guide having a cutter guide and being mounted for translation along the alignment guide; and sliding the distal cut guide along the alignment guide until the distal cut guide is adjacent the side of the femur.
 25. The method of claim 24 further comprising the steps of: positioning the alignment guide so that a reference surface on the alignment guide contacts a distal femoral condyle; and guiding a cutter with the distal cut guide to make a cut at a predetermined distance from the femoral condyle.
 26. The method of claim 24 further comprising the steps of: positioning the alignment guide so that a reference surface on the alignment guide contacts the intramedullary sulcus; and guiding a cutter with the distal cut guide to make a cut at a predetermined distance from the intramedullary sulcus.
 27. A tibial cut guide assembly comprising: a support having a longitudinal support axis; a cross member mounted on the support, the cross member having a cross member axis perpendicular to the support axis, the cross member axis and support axis defining a guide plane, the cross member having a slope reference oriented at a predetermined slope angle relative to the guide plane; a cut guide having a cross member engaging end and a cutter guide, the cross member engaging end being mounted on the cross member in engagement with the slope reference, the cutter guide defining a cut plane that is oriented at a predetermined slope angle relative to the guide plane as determined by the slope reference.
 28. The tibial cut guide assembly of claim 27 further comprising a plurality of interchangeable cross members, each interchangeable cross member having a slope reference oriented at a different predetermined slope angle relative to the guide plane.
 29. The tibial cut guide assembly of claim 27 wherein the cut guide is mounted on an arm projecting upwardly and inwardly from the cross member to position the cutter guide adjacent a tibia to be cut.
 30. The tibial cut guide assembly of claim 27 wherein the cut guide is translatable along the cross member from a first position to a second position, the cutter guide defining parallel planes in the first and second position.
 31. The tibial cut guide assembly of claim 30 wherein the cross member is translatable up and down along the support axis.
 32. The tibial cut guide assembly of claim 27 further comprising a proximal adjustment mechanism actuable to change the spacing of a proximal end of the support and a proximal end of a tibia to change the angle of the support axis relative to a tibial axis.
 33. The tibial cut guide assembly of claim 32 wherein the proximal adjustment mechanism comprises a screw threadingly engaging the support and abuttable with a proximal end of a tibia.
 34. A tibial cut guide assembly for cutting a proximal end of a tibia having a proximal end, a distal end, a tibial shaft, a tibial axis along the shaft, an anterior side parallel to a frontal plane, a medial side parallel to a sagittal plane, and a lateral side parallel to said sagittal plane, the tibial cut guide assembly comprising: a support having a support axis, the support being mountable on said tibia with the support axis parallel to said tibial axis; a cut guide, the cut guide being mounted on the support with the cut guide oriented to guide a cutter obliquely toward said tibia between the anterior side and one of the medial and lateral sides of said tibia to cut the proximal end of said tibia when the support is mounted on said tibia.
 35. The tibial cut guide assembly of claim 34 further comprising a cross member mounted on the support connecting the support and cut guide, the cross member having a cross member axis perpendicular to the support axis, the cross member axis and support axis defining a guide plane, the guide plane being positionable parallel to the frontal plane and the tibial axis, the cross member having a slope reference oriented at a predetermined slope angle relative to the guide plane.
 36. The tibial cut guide assembly of claim 35 wherein the cut guide has a cross member engaging end and a cutter guide, the cross member engaging end being mounted on the cross member in engagement with the slope reference, the cutter guide defining a cut plane that is oriented at a predetermined slope angle relative to the guide plane as determined by the slope reference, the cutter guide being translatable along the cross member from a first position to a second position, the cutter guide defining parallel planes in the first and second position.
 37. A tibial cut guide assembly comprising: an alignment bar having a longitudinal alignment bar axis; a boom mounted on the alignment bar, the boom having a boom axis perpendicular to the alignment bar axis, the boom axis and alignment bar axis defining a guide plane, the boom having a slope reference oriented at a predetermined slope angle relative to the guide plane; a cut guide having a boom engaging end and a cutter guide, the boom engaging end being mounted on the boom in engagement with the boom slope reference, the cutter guide defining a cut plane that is oriented at a predetermined slope angle relative to the guide plane as determined by the boom slope reference.
 38. The tibial cut guide assembly of claim 37 wherein the cut guide slidingly engages the boom so that the cut guide can slide along the boom from a first position further from the alignment bar to a second position nearer to the alignment bar while maintaining the cut plane at a constant angle to the guide plane.
 39. The tibial cut guide assembly of claim 38 wherein the boom is mounted for translation along the alignment bar axis so that moving the boom along the alignment bar axis changes the level of the cut plane.
 40. The tibial cut guide assembly of claim 37 further including a depth gauge, the depth gauge including a blade having a reference end, the depth gauge being mounted on the assembly with the reference end a predetermined fixed distance from the cut plane as measured along the alignment bar axis.
 41. The tibial cut guide assembly of claim 37 wherein the cutter guide comprises a saw blade slot defining a plane for a saw blade.
 42. A method for cutting a proximal end of a tibia having a proximal end, a distal end, a tibial shaft, a tibial axis along the shaft, an anterior side parallel to a frontal plane, a medial side parallel to a sagittal plane, and a lateral side parallel to said sagittal plane, the method comprising the steps of: mounting a cut guide on the tibia with the cut guide oriented to guide a cutter obliquely toward the tibia between the anterior side and one of the medial and lateral sides of the tibia; and guiding a cutter obliquely toward the tibia with the cut guide to cut the proximal end of the tibia.
 43. The method of claim 42 further comprising the steps of: providing a support having a support axis; mounting the support on said tibia with the support axis parallel to the tibial axis; mounting the cut guide on the support.
 44. The method of claim 43 wherein the step of mounting the support includes mounting the support on the anterior surface of the tibia.
 45. The method of claim 44 further comprising the step of adjusting the cut guide mediolaterally while maintaining parallel cut planes.
 46. A method for cutting a proximal end of a tibia having a proximal end, a distal end, a tibial shaft, a tibial axis along the shaft, an anterior side parallel to a frontal plane, a medial side parallel to a sagittal plane, and a lateral side parallel to said sagittal plane, the method comprising the steps of: providing a tibial alignment bar having an alignment bar axis and a tibial boom mounted on the alignment bar for translation along the alignment bar axis, the tibial boom having a boom axis perpendicular to the alignment bar axis, the alignment bar axis and boom axis together defining a guide plane, the boom further including a posterior slope reference defining a predetermined angle relative to the guide plane; mounting the alignment bar on said tibia with the alignment bar axis parallel to the tibial axis; providing a cut guide; mounting the cut guide on the boom for translation along the boom axis and in engagement with the posterior slop reference such that the cut guide is oriented to guide a cutter obliquely toward the tibia between the anterior side and one of the medial and lateral sides of the tibia to cut a planar surface at the predetermined angle relative to the guide plane; and guiding a cutter obliquely toward the tibia with the cut guide to cut the proximal end of the tibia.
 47. The method of claim 46 further including the steps of: providing a tibial alignment bar with a selection of booms having different posterior slope reference angles; determining a desired slope; picking a boom corresponding to the desired slope.
 48. The method of claim 46 further comprising the step of making an incision on the at least one of the medial and lateral sides of a knee to expose the proximal tibia from the side.
 49. The method of claim 48 further comprising the step of adjusting the cut guide mediolaterally to be adjacent until it is obliquely adjacent the proximal tibia.
 50. The method of claim 49 further comprising the step of positioning the tibial boom along the alignment bar axis to set the depth of the tibial cut.
 51. The method of claim 46 further comprising the steps of: setting a proximal end of the tibial alignment bar adjacent the proximal end of the tibia at a desired mediolateral position and the distal end of the alignment bar adjacent the distal end of the tibia at a desired mediolateral position to establish mediolateral vertical reference axis relative to which the cut guide sets the varus-valgus angle; independently of the mediolateral setting, setting the proximal end of the alignment bar at a desired anteroposterior position relative to the proximal end of the tibia and the distal end of the alignment bar at a desired anteroposterior position relative to the distal end of the tibia to establish an anteriorposterior vertical reference axis relative to which the cut guide sets the posterior slope; adjusting the cut guide mediolaterally while maintaining parallel cut planes having the same varus-valgus angle and posterior slope; adjusting the proximal distal position of the cut plane independently of mediolateral position to set the depth of cut; and guiding a cutter with the cut guide to cut the tibia at the independently established depth, varus-valgus angle, and posterior slope.
 52. A guide for establishing a position reference on a distal portion of a femur having a distal end, an anterior surface, a medial side surface, a lateral side surface, posterior condyles, and anatomic landmarks, the guide comprising: a base having a reference surface for engaging said distal end; and a pin guide mounted for rotation relative to the base, the pin guide including at least one pin guide hole for guiding a reference pin to engage one of said medial and lateral side surfaces of said distal femur.
 53. The guide of claim 52 wherein the pin guide has an alignment portion for aligning with anatomic landmarks on said distal femur.
 54. The guide of claim 53 further comprising a foot connected to the base, the foot extending at an angle from the reference surface to engage said posterior condyles to establish a posterior size reference.
 55. The guide of claim 54 further comprising a plate, the plate rotationally mounted to the base and the pin guide mounted on the plate so that as the pin guide rotates relative to the base the pin guide also rotates relative to the base.
 56. The guide of claim 55 wherein the base includes a plurality of rotational alignment holes and the plate includes a plurality of alignment holes, different pairs of holes aligning at different angles of rotation between the base and plate.
 57. The guide of claim 56 wherein the pin guide is mounted for translation relative to the plate so that the plate can be rotated to set the rotation of the pin guide hole relative to the base and the pin guide can be translated relative to the plate to set the spacing of the pin guide hole from the base.
 58. The guide of claim 57 further including an anterior probe mounted for translation relative to the plate, the anterior probe having a probe tip for engaging said femoral anterior surface, the probe having size indicia to indicate the distance the probe is translated relative to the plate.
 59. The guide of claim 58 further including a feeler gauge that indexes the translation of the pin guide relative to the plate to the translation of the probe relative to the plate so that sizing information determined by the probe is reflected in the position of the pin guide.
 60. The guide of claim 59 wherein the pin guide is mounted for mediolateral translation relative to the plate so that it can be moved to a position adjacent the side of the femur.
 61. A guide for establishing a position reference on a distal portion of a femur having a distal end, an anterior surface, a posterior surface, a medial side surface, a lateral side surface, posterior condyles, a femoral axis, and anatomic landmarks, the guide comprising: means for establishing a desired rotation angle relative to said femoral axis; and means for establishing a desired A/P position between said anterior and posterior surfaces of said femur; and means for establishing a datum on said distal femur that records the rotation angle and A/P position in such a way that the datum can be subsequently referenced by bone cutting guides to produce bone cuts relative to the rotation and position information.
 62. The guide of claim 61 wherein the datum comprises an element selected from the group consisting of a pin, a hole, a slot, and a notch.
 63. The guide of claim 61 wherein the datum is able to be referenced by subsequent instruments to establish the varus-valgus angle, external rotation, and anteroposterior position of bone cuts.
 64. The guide of claim 61 wherein the means for establishing a desired rotation angle comprises a base having a reference surface for engaging said distal end of said femur and a datum guide mounted for rotation relative to the base, the datum guiding the positioning of a datum on one of said medial and lateral side surfaces of said distal femur.
 65. A method for establishing a position reference datum on a distal portion of a femur having an anterior surface, a posterior surface, posterior condyles, a femoral axis, medial and lateral epicondyles, and an A/P axis, the method comprising the steps of: determining a desired rotation angle relative to the femoral axis; determining a desired A/P position between the anterior and posterior surfaces of the femur; creating a datum on the distal femur that records the rotation angle and A/P position in such a way that the datum can be subsequently referenced by bone cutting guides to produce bone cuts relative to the rotation and position information.
 66. The method of claim 65 wherein the step of determining a desired rotation angle is accomplished by aligning a datum guide relative to an anatomic reference selected from the group consisting of the femoral posterior condyles, a line drawn between the medial and lateral femoral epicondyles, and a line drawn along the distal femoral A/P axis.
 67. The method of claim 65 wherein the step of determining a desired A/P position comprises contacting the anterior femoral surface with a probe.
 68. The method of claim 65 wherein the step of creating a datum comprises a step selected from the group consisting of drilling at least one hole, cutting at least one slot, and setting at least one pin in the femur.
 69. The method of claim 65 further comprising the steps of: providing a pin guide; establishing the rotation by aligning the pin guide with one of the femoral posterior condyles, a line drawn between medial and lateral epicondyles, and a line drawn along the A/P axis; establishing the A/P position by offsetting the pin guide from a probe in contact with the anterior surface; and establishing the datum by guiding at least one pin through the pin guide and into the femur.
 70. The method of claim 69 wherein the step of establishing the datum comprises guiding at least two pins through the pin guide and into the femur.
 71. The method of claim 65 further comprising the steps of: referencing the datum with a cut guide to orient the cut guide relative to the rotation angle and A/P position; and guiding a cutter with the cut guide to cut the femur.
 72. The method of claim 71 further comprising the step of making an incision on the at least one of the medial and lateral sides of a knee to expose the femur from the side and performing the other steps through the incision from the side of the knee.
 73. A method for establishing a position reference datum on a distal portion of a femur having a distal end, an anterior surface, a posterior surface, a medial side surface, a lateral side surface, posterior condyles, a femoral axis, and anatomic landmarks, the method comprising the steps of: providing a guide having a base and a pin guide mounted for rotation and translation relative to the base; placing the base against the distal end of said femur; rotating the pin guide relative to the base to a desired rotation angle; translating the pin guide relative to the base to a desired A/P position; and inserting at least one pin into said femur with the pin guide, the at least on pin fixing the rotation angle and A/P position for future reference.
 74. The method of claim 73 wherein the step of inserting at least one pin comprises inserting at least two pins.
 75. The method of claim 73 further comprising the steps of: mounting a cut guide on the pin to orient the cut guide at the desired rotation angle and A/P position; and guiding a cutter with the cut guide to make anterior, posterior and chamfer cuts on the distal femur.
 76. The method of claim 75 further comprising the steps of: making an incision on one of the medial and lateral sides of the knee to expose the femur from the side; and performing the other steps through the incision from the side of the knee.
 77. An apparatus for guiding a cutter to cut a femur having a datum established on it, the datum fixing a desired external rotation and A/P position, the apparatus comprising: a cut guide for guiding a cutter to cut said femur; and means for engaging said datum to orient the cut guide to guide a cutter to cut said femur at said desired external rotation and A/P position.
 78. The apparatus of claim 77 wherein the cut guide comprises a saw blade guide.
 79. The apparatus of claim 78 wherein the saw blade guide includes slots for guiding a saw blade to form anterior, posterior, and chamfer cuts on said femur.
 80. The apparatus of claim 79 wherein the guide includes a side portion and a distal portion, the slots sweeping from the side portion to the distal portion to allow cutting from the side and distally.
 81. The apparatus of claim 77 wherein the means for engaging said datum comprises a hole formed in the cut guide.
 82. A guide for guiding a cutter to cut a profile on a distal femur, the femur having at least one pin inserted into the side of the femur fixing a desired external rotation and A/P position, the guide comprising: a distal portion having inner and outer distal surfaces; a side portion having inner and outer side surfaces with at least one hole extending through the side from the inner to the outer side surface for receiving said at least one pin to set the guide at said desired external rotation and A/P position; and a cut guide for guiding a cutter to cut said femur at said desired external rotation and A/P position.
 83. The guide of claim 82 wherein the cut guide comprises a saw guide slot.
 84. The guide of claim 83 wherein the saw guide slot sweeps from the side portion to the distal portion.
 85. The guide of claim 82 wherein the distal portion further comprising an opening for visualizing the distal end of the femur.
 86. The guide of claim 82 wherein the at least one hole is slotted so that the guide can slide between a proximal position and a distal position on the pin to permit the inner, distal guide surface to be positioned in contact with said distal femur.
 87. The guide of claim 86 further comprising a distal fixation hole to receive a fastener to fix the guide in a position with the inner, distal guide surface in contact with said distal femur.
 88. A method for cutting a distal portion of a femur having an anterior surface, a posterior surface, and a femoral axis, the method comprising the steps of: determining a desired rotation angle relative to the femoral axis; determining a desired A/P position between the anterior and posterior surfaces of the femur; creating a datum on the distal femur that records the rotation angle and A/P position; referencing the datum with a cut guide to orient the cut guide relative to the rotation angle and A/P position; and guiding a cutter with the cut guide to cut the femur.
 89. The method of claim 88 wherein the cut guide comprises a saw guide slot and the step of guiding a cutter comprises guiding a saw blade.
 90. The method of claim 89 wherein the saw guide slot sweeps from a side portion to distal portion and further comprising the step of guiding a saw blade through the slot from the side and moving the saw blade through the swept slot to guide the saw blade through the slot distally.
 91. The method of claim 88 wherein the cut guide further includes window for viewing the distal end of the femur and further comprising the step of viewing the cutting of the distal end of the femur through the window.
 92. The method of claim 88 wherein the datum is a pin and the cut guide has a hole for receiving the pin, the method further comprising the step of engaging the pin with the hole to position the cut guide.
 93. The method of claim 92 wherein the hole comprises an elongated slot to permit the cut guide to slide proximally and distally on the pin, the method further comprising sliding the cut guide proximally on the pin until it abuts the distal femur.
 94. The method of claim 93 wherein the cut guide further comprises a distal fixation hole, the method further comprising the step of inserting a fastener through the fixation hole to hold the cut guide against the distal femur.
 95. The method of claim 88 further comprising the steps of: making an incision on at least one of the medial and lateral sides of a knee to expose the femur from the side; and performing the other steps through the incision from the side of the knee.
 96. A cut guide for a femur having an anterior side, a posterior side, a proximal end, and a distal end, the cut guide comprising: an anterior body portion having an outer anterior surface, an inner anterior surface, and an anterior cut guide surface; a distal body portion having an outer distal surface, an inner distal surface, and a distal cut guide surface, the distal body portion extending from the anterior body portion at an angle, the distal cut guide surface being aligned with the anterior cut guide surface; and a cutter guidable from the distal cut guide surface to the anterior cut guide surface to cut the anterodistal aspect of said femur along an angle from posterior and distal to anterior and proximal.
 97. The cut guide of claim 96 wherein the anterior cut guide surface comprises an anterior chisel guide and the posterior cut guide surface comprises a posterior chisel guide and the cutter comprises a chisel.
 98. The cut guide of claim 97 wherein the anterior chisel guide comprises a slot extending from the outer anterior surface to the inner anterior surface, the distal chisel guide comprises a slot extending from the outer distal surface to the inner distal surface and the chisel comprises a cross sectional shape matching the anterior and distal chisel slots so that the chisel is insertable through the chisel slots from the distal chisel slot to the anterior chisel slot.
 99. The cut guide of claim 98 wherein the slots are three sided and the chisel comprises a corresponding three sided shape.
 100. The cut guide of claim 99 further comprising at least one distal drill guide hole formed through the distal body portion from the outer distal surface to the inner distal surface to guide a drill to form at least one hole in the distal end of the femur at a predetermined location relative to the slots.
 101. The cut guide of claim 97 further comprising medial and lateral articular condyles having articulating surfaces formed thereon permitting trial fitting of the cut guide to simulate the fit of a corresponding femoral implant relative to the tibia.
 102. The cut guide of claim 101 further comprising a patellar articular surface formed thereon permitting trial fitting of the cut guide to simulate the fit of a corresponding femoral implant relative to the patella.
 103. The cut guide of claim 97 further comprising an inner box profile corresponding to the inner box profile of a femoral implant.
 104. A method for cutting the anterodistal aspect of a femur having an anterior side, a posterior side, a proximal end, and a distal end, the method comprising the steps of: mounting a cut guide on the femur, the cut guide having a chisel guide; and guiding a chisel with the chisel guide to cut the anterodistal aspect of the femur along an angle from posterior and distal to anterior and proximal.
 105. The method of claim 104 wherein the chisel guide comprises an anterior chisel slot and a distal chisel slot and the chisel comprises a cross sectional shape matching the anterior and distal chisel slots, the method further comprising the step of inserting the chisel through the slots from the distal chisel slot to the anterior chisel slot.
 106. The method of claim 105 wherein the cut guide further comprises at least one drill guide hole, the method further comprising the step of guiding a drill with the at least one drill guide hole to drill a hole in the distal end of the femur at a predetermined location relative to the slots.
 107. The method of claim 104 wherein the cut guide further comprises medial and lateral articular condyles having articulating surfaces formed thereon, the method further comprising the step of performing a trial fitting of the cut guide on the femur and articulating it relative to the tibia to simulate the fit of a corresponding femoral implant relative to the tibia, before the step of guiding a chisel to cut the femur.
 108. The method of claim 104 wherein the cut guide further comprises a patellar articular surface formed thereon, the method further comprising the step of performing a trial fitting of the cut guide on the femur and articulating it relative to the patella to simulate the fit of a corresponding femoral implant relative to the patella, before the step of guiding a chisel to cut the femur.
 109. The method of claim 104 further comprising the steps of first making an incision on one of the medial and lateral sides of the knee joint to expose the femur from the side and performing the other steps through the incision from the side of the knee.
 110. The method of claim 104 further comprising the steps of providing a femoral notch guide comprising a notch cut guide and a protrusion for engaging the cut in the anterodistal aspect of the femur, engaging the protrusion with the cut in the anterodistal aspect of the femur to align the femoral notch cut guide, and guiding a cutter with the notch cut guide to cut a notch in the femur.
 111. The method of claim 106 further comprising the steps of providing a femoral notch guide comprising a notch cut guide and at least one protrusion for engaging the at least one hole drilled in the distal end of the femur, engaging the protrusion with the hole in the distal end of the femur to align the femoral notch cut guide, and guiding a cutter with the notch cut guide to cut a notch in the femur.
 112. A method of total knee arthroplasty comprising the steps of: making an incision on at least one of the medial and lateral sides of a knee to expose the knee joint from the side; placing a patella cut guide adjacent the patella; guiding a cutter with the patella cut guide through the incision to cut the patella from the side of the knee; placing a femoral cut guide adjacent the femur; guiding a cutter with the femoral cut guide through the incision to cut the femur from the side of the knee; placing a tibial cut guide adjacent the tibia; and guiding a cutter with the tibial cut guide through the incision to cut the tibia from the side of the knee.
 113. The method of claim 112 wherein the step of cutting the femur comprises cutting the distal end of the femur and wherein the method further comprises the steps of: establishing a datum on the femur engageable from the side of the knee to fix the desired external rotation and anteroposterior position of subsequent bone cuts; engaging the datum with a cut guide to orient the cut guide in the desired external rotation and anteroposterior position; and cutting the distal femur profile from the side of the knee.
 114. The method of claim 112 wherein the step of cutting the patella further comprises cutting the patella while maintaining the patella in its normal anteroposterior orientation relative to the femur. 